1. Field of the Invention
The present invention relates to a drain valve device for a cleaning water tank, and a drain valve for the drain valve device.
2. Description of the Related Art
Conventionally, although a flapper valve or a drain valve is used for carrying out a water discharge and a water stop by opening and closing a draining port, in a cleaning water tank for storing a cleaning water to clean a toilet bowl, the flapper valve would be deteriorated and/or worn by being exposed in water for a long period of time, and by carrying out the opening and closing operations repeatedly, when the flapper valve used for a long period of time.
As a result, the deteriorated flapper valve becomes deformed and/or a pinhole is formed therein, and a water-tightness is no longer maintained, thereby causing a water leakage. For this reason, it is configured so that the deteriorated flapper valve is replaced with a new flapper valve.
When changing the flapper valve, occasionally a worker may attach a non-conformable flapper valve mistakenly, since there are different types of flapper valves, in matching the specifications of the cleaning water tanks.
However, as disclosed in JP-A-9-291580, for example, since a mechanism for preventing a non-conformable flapper valve from being attached is not provided in the conventional drain valve device for the cleaning water tank, there is only the way such that the worker needs to replace a conformable flapper valve, and as a result, it has been difficult to securely prevent the non-conformable flapper valve from being attached.
As described above, at the time of changing a flapper valve, when a non-conformable flapper valve is attached, there is a problem such that an amount of cleaning water discharged from a cleaning water tank becomes more than a required amount, or less than the required one, and as a result, a predetermined cleaning function could not be performed.
In order to solve such problems, the inventors of the present invention have found effective prevention measures by conducting the various kinds of investigations and examinations, etc.